1. Field of the Invention
This invention relates to a sound reproduction device of random selecting type. More particularly, this invention relates to a device in which the timing for releasing the stylus force imparted to the pickup of the device and then letting the pickup return to the starting point of sound reproduction is rendered irregular with respect to the timing where the pickup engages the introductory part of a record groove out of the plurality of record grooves, thereby making it is possible to enjoy the reproduced record items in a random manner.
2. Prior Art
Heretofore, there have been provided simplified sound reproduction devices designed for sound reproduction in a manner of random selection. These devices generally comprise:
a swing arm for releasing stylus force and carrying a free gear having an integrally formed upwardly facing cam;
a center gear fixed at the center of a record disc so as to be capable of being rotated integrally with the record disc; and
a sound transmitting member disposed above the record disc and supported in a cantilevered manner to lift it upward by said upwardly facing cam.
In these conventional devices, once the pickup arrives at the end point of sound reproduction, it urges the swing arm so as to permit the free gear to mesh with the center gear causing the free gear to rotate with the rotation of the center gear, and in turn, actuate the cam to release the stylus force.
In this device, the number of parts is increased by interposing the free gear and using a backlash, often found in this kind of device, for randomly releasing stylus force as desired.
However, the extent of irregularity of randomness present in devices made according to the prior art was not satisfactory. The devices as previously designed gradually became inclined to select only specific items, afer having been used for large number of sound reproductions. This tendency becomes more marked when the device is made with more precision. Thus, the advantage obtained by increasing the number of parts is eliminated with respect to the attractive merit of irregularity or randomness in selecting the items to be played.